Major Crimes detectives are investigating a homicide at Eastern State Hospital in Medical Lake involving a female patient killing a male patient at the facility early Tuesday morning.

According to Spokane County Sheriff's deputies, Eastern State Hospital staff found a man's body around 2:30 a.m. Tuesday. A female patient, identified as 30-year-old Amber Roberts, has been booked into the Spokane County Jail on a single count of premeditated 1st degree murder.

"We're not sure right now whether there was some type of altercation. We're just not sure of the dynamics of how it took place, of what transpired this morning," Spokane County Sheriff's Deputy Craig Chamberlin said.

Both Roberts and the victim were patients being held in the Forensic Services Unit at the psychiatric hospital. A DSHS spokesperson said people living in that ward have been committed by a judge and involved in a criminal case. They are either being held for observation or as a result of pleading not guilty by reason of insanity.

There are thirty people to a ward and the remaining patients in that ward have been transported to a different are.

Deputies wouldn't say why Roberts or the victim were in the hospital or how the man was killed, however Roberts was admitted to Eastern State in 2003 after an Oct. 28, 2003 incident where she carjacked a 72-year-old woman, choked her so she could take her car and then left the victim in Yakima, where authorities found her semi-conscious.

Roberts drove the woman's car to Spokane, where she was later apprehended and charged with robbery and kidnapping. She plead not guilty by reason of insanity and was subsequently admitted to Eastern State.

DSHS will conduct an internal investigation into what happened and determine what, if anything, went wrong and how to prevent it from happening again. Spokesperson John Wiley said this is an extremely rare occasion and long-term employees said they cannot remember something like this happening before.

An autospy is being performed on the victim Tuesday; the medical examiner will release that person's name at a later time.

The early morning killing of that Eastern State patient is the latest in a series of widely publicized incidents involving the hospital.

In 2008 the Washington State Patrol was involved in an investigation of rape at the hospital At the time investigators said there were no type of barriers that prevent patients from moving between the male and female wards..

In 2009, criminally insane killer Philip Paul walked away from a hospital field trip to the Spokane County Fair. A statewide manhunt was launched and he was found three days later south of Yakima.